Nesting and Egg Incubation in Dinosaurs: Morphological and Statistical Investigations into the Study of Eggs, Eggshells, and Nests
Bibliographic record
Abstract
Archosaurs (e.g., crocodylians, dinosaurs, and birds) are the most diverse and successful terrestrial vertebrates. An understanding of the nesting strategies in both extinct (e.g., non-avian dinosaurs) and extant archosaurs (i.e., crocodylians and birds) is crucial for advancement of our knowledge on the evolution and diversification of this group. However, nesting methods and behaviors of non-avian dinosaurs are still poorly understood due to the limitations of the fossil record. In this dissertation, certain features of eggs and nests in dinosaurs (e.g., clutch size, egg mass, substrates of nests, water vapor conductance of eggs, and eggshell porosity) are compared with those of their closest living relatives (i.e., birds and crocodylians) and aspects of dinosaur nesting (i.e., nest type, incubation behavior, incubation heat source, and incubation period) are inferred and reconstructed. Findings in this dissertation suggest that nests and nesting styles among non-avian dinosaurs were diverse, and that bird-like traits were acquired throughout their evolution. Analyses of eggs and eggshell porosity indicate that more basal dinosaurs (i.e., ornithischians, sauropodomorphs, Lourinhanosaurus) completely covered their eggs with nest materials during incubation, although more derived forms (e.g., oviraptorosaurs, troodontids) used open nests, like modern birds, in which the eggs were not fully buried. The lithologies of the clutches of basal dinosaurs reveal their nests were probably incubated with external heat sources (e.g., microbial respiration, solar radiation), like those of modern crocodylians and megapode birds. Distribution and lithologies of some ornithischian and some sauropodomorph clutches show that heat from microbial respiration, in particular, was used for incubation, whereas other sauropodomorphs may have used inorganic heat sources, such as solar radiation. More derived dinosaurs (i.e., maniraptorans) had eggshell porosities and clutch lithologies that indicate their nests were partially open, indicating that these taxa brooded their eggs. Regardless of the type of nest, heat source, or incubation behavior, incubation period of most non-avian dinosaurs examined was relatively short, more comparable to that of birds than crocodylians. Major dinosaur (and archosaur) clades show diversity in their nesting and incubation, and also reveal a transition to more bird-like nesting features through evolution.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".